SMA wire driving device, closed-loop control method thereof and electronic device

Abstract

An SMA wire driving device, a closed-loop control method thereof and an electronic device are provided, which relates to the technical field of actuators. The SMA wire driving device includes a stationary part, a movable part being movable relative to the stationary part, and an SMA wire configured to drive the movable part to move relative to the stationary part, where a sampling resistor is connected in series with the SMA wire. By the SMA wire driving device, a displacement of the movable part relative to the stationary part can be detected by acquiring a voltage of the sampling resistor connected in series with the SMA wire. Based on the SMA wire driving device, a closed-loop control method is further provided, which has a small computation amount, so that the SMA wire can be rapidly controlled, improving driving effect of the SMA wire driving device.

The invention claimed is: 
     
       1. A closed-loop control method for a shape memory alloy (SMA) wire driving device, wherein the SMA wire driving device comprises an SMA wire pair, a sampling resistor, a movable part, and a stationary part, comprising:
 acquiring a first voltage V 1  of the sampling resistor when the sampling resistor is connected in series with only a first SMA wire in the SMA wire pair; 
 acquiring a second voltage V 2  of the sampling resistor when the sampling resistor is connected in series with only a second SMA wire in the SMA wire pair; 
 acquiring a current voltage reciprocal difference of the sampling resistor according to the first voltage V 1  and the second voltage V 2 , wherein the current voltage reciprocal difference is 
 
       
         
           
             
               
                 
                   1 
                   
                     V 
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                   1 
                   
                     V 
                     2 
                   
                 
               
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         acquiring a target voltage reciprocal difference of the sampling resistor according to a target displacement, wherein the target displacement represents a displacement to be made by the movable part to move to a predetermined position relative to the stationary part; 
         acquiring a deviation of the current voltage reciprocal difference from the target voltage reciprocal difference; and 
         when the deviation is greater than a threshold value, repeatedly adjusting driving signal applied to the SMA wire pair and acquiring the current voltage reciprocal difference in response to the adjusted driving signal, until the deviation is less than the threshold value. 
       
     
     
       2. The closed-loop control method according to  claim 1 , wherein the acquiring a target voltage reciprocal difference of the sampling resistor according to a target displacement comprises:
 acquiring a first target voltage V 1 ′ and a second target voltage V 2 ′ of the sampling resistor according to the target displacement; and 
 calculating the target voltage reciprocal difference according to the first target voltage V 1 ′ and the second target voltage V 2 ′, wherein the target voltage reciprocal difference is 
 
       
         
           
             
               
                 1 
                 
                   V 
                   1 
                   ′ 
                 
               
               - 
               
                 
                   1 
                   
                     V 
                     2 
                     ′ 
                   
                 
                 . 
               
             
           
         
       
     
     
       3. The closed-loop control method according to  claim 1 , further comprising:
 reducing, when the deviation is less than the threshold value, an amplitude of adjusting the driving signal applied to the SMA wire pair to maintain the driving signal applied to the SMA wire pair in a target dynamic range. 
 
     
     
       4. The closed-loop control method according to  claim 1 , further comprising:
 detecting a plurality of voltage reciprocal differences of the sampling resistor corresponding to a plurality of different displacements of the movable part relative to the stationary part, and acquiring a first relationship between the displacement and the voltage reciprocal difference. 
 
     
     
       5. The closed-loop control method according to  claim 4 , further comprising:
 acquiring the target displacement of the movable part relative to the stationary part, and 
 acquiring the voltage reciprocal difference corresponding to the target displacement according to the first relationship between the displacement and the voltage reciprocal difference. 
 
     
     
       6. The closed-loop control method according to  claim 1 , further comprising:
 detecting a plurality of displacements of the movable part relative to the stationary part corresponding to a plurality of different voltage reciprocal differences of the sampling resistor, and acquiring a second relationship between the displacement and the voltage reciprocal difference. 
 
     
     
       7. The closed-loop control method according to  claim 6 , further comprising:
 acquiring the target displacement of the movable part relative to the stationary part, and 
 acquiring the voltage reciprocal difference corresponding to the target displacement according to the second relationship between the displacement and the voltage reciprocal difference. 
 
     
     
       8. An electronic device, comprising:
 at least one processor; and 
 a memory in communication connection with the at least one processor, 
 wherein the memory stores instructions which, when being executed by the at least one processor, cause the at least one processor to perform the closed-loop control method according to  claim 1 .